1. Field of the Invention
The present invention relates to a disconnection and short detecting circuit included in a semiconductor integrated circuit device.
2. Description of the Background Art
For example, in FIG. 1 of Japanese Patent Laid-Open Publication No. 2003-143239, a non-inverting clock signal and an inverting clock signal, which are in opposite phases, are inputted via a terminating resistor 21 to a non-inverting input terminal 24 and an inverting input terminal 25, respectively. The non-inverting and the inverting clock signals are then inputted to a positive (+) terminal and a negative (−) terminal of a comparator 23. Here, the comparator 23 functions as a receiver of a differential clock signal composed of a non-inverting clock signal and an inverting clock signal. The output of the comparator 23 is used for operating clocks within a semiconductor device, for example.
Besides the aforesaid Publication No. 2003-143239, Japanese Patent Laid-Open Publication No. 6-85717 discloses information related to the receiving of a differential clock signal.
The recent semiconductor integrated circuit devices often employ surface mount type packages such as quad flat package (QFP) and small outline package (SOP). Therefore, the pin pitch is narrowed to make it difficult to perform inspection with use of a conventional probe.
Hence, there has been employed boundary scan function based on the standard of joint test action group (JTAG), and the like. The term “boundary scan function” denotes the following test function. That is, a register, being called “cell,” which performs operation equivalent to a test probe, is disposed between each pin and a core circuit in a semiconductor integrated circuit device, and respective cells are coupled to configure a shift register. This shift register is then controlled to detect the input of a test code to the core circuit and the corresponding response from the core circuit, thereby implementing the test function.
The boundary scan function, however, failed to detect disconnection and short of a signal line transmitting a differential clock signal.